Deflection coils producing pincushion and barrel deflection fields

ABSTRACT

A magnetic deflection apparatus for displacing an electron beam in a cathode ray tube, and more particularly a deflection yoke for use in a color television receiver which comprises a plurality of deflection coil units arranged contiguously in the axial direction of the tube, whereby the deflection field at the central portion of the deflection coil units or the deflection field on the electron gun side of the central portion has a barrel field distribution and the deflection field on the screen side has a pincushion field distribution, thereby easily correcting pincushion and convergence distortions.

United States Patent [191 Kadota Nov. 19, 1974 DEFLECTION COILSPRODUCING PINCUSHION AND BARREL DEFLECTION FIELDS [75] Inventor: TokuzoKadota, Kadoma, Japan [73] Assignee: Matsuhita Electric Industrial Co.,

Ltd., Osaka, Japan [22] Filed: Feb. 12, 1973 [21] Appl. No; 331,600

[30] Foreign Application Priority Data Feb. 16, 1972 Japan 47-16662 Feb.28, 1972 Japan 47-20883 Feb. 28. 1972 Japan 47-20884 [52] U.S. Cl.335/210, 335/213 [51] Int. Cl. H0lf 7/00 [58] Field of Search 335/210,213; 313/75, 76, 313/77 [56] References Cited UNITED STATES PATENTS2.617.059 11/1952 Neeteson 313/75 3,735,193 5/1973 lkeuchi 33 /213 X3,735,299 5/1973 Gross et a1 335/213 3.763.452 10/1973 lkeuchi H 335/213Primary ExaminerG. Harris Attorney, Agent, or Firm-Stevens, Davis,Miller & Mosher [5 7 ABSTRACT A magnetic deflection apparatus fordisplacing an electron beam in a cathode ray tube, and more particularlya deflection yoke for use in a color television receiver which comprisesa plurality of deflection coil units arranged contiguously in the axialdirection of the tube, whereby the deflection field at the centralportion of the deflection coil units or the deflection field on theelectron gun side of the central portion has a barrel field distributionand the deflection field on the screen side has a pincushion fielddistribution, thereby easily correcting pincushion and convergencedistortions.

14 Claims, 21 Drawing Figures PATENIE NOV 1 91974 sum 10F 5 PRIOR ARTSm: 2 m0 MQEIEQQE \J V SCREEN ELECTRON GUN DISTANCE PATENTEL HEY I 9I974 SHEET 2 [IF 5 FIG. 4

DISTANCE SCREEN ELECTRON GUN I FIG. 6

Sum 2523: 6 E522 N O R ELECT GUN DISTANCE PATENI rm 1 9 I974 sum 3 or 5nocos B FIG.

SE @5232 6 Q523 SCREEN [NSTANCE ELECTRON GUN FIG.

FIG.

PATENTEL HEY I 9 I974 SHEU S I)? 5 FIG.

FIG. l4

FIG.

FIG.

DEFLECTION COILS PRODUCING PINCUSI-IION AND BARREL DEFLECTION FIELDS Thepresent invention relates to a magnetic deflection apparatus used in acolor television receiver to displace an electron beam therein.

The characteristics of a deflection yoke employed in a color televisionreceiver has various effects on the picture quality of a color picturetube. While some of these effects may be corrected by means of circuitdesigning, there are some others which may not be readily corrected bycircuit designing and which are thus entirely dependent on thecharacteristics of a deflection yoke used. For instance, whilepincushion distortion may be corrected by means of a specially designedcircuit, it is difficult to correct convergence distortion by means ofcircuit designing. As a result, since the abovementioned convergencedistortion and other cannot be corrected by means of circuit designing,it has been customary to discard the deflection yoke as a reject, if thevariation in the characteristic of a deflection yoke caused during themanufacturing process exceeds the allowable limits.

It is therefore an object of the present invention to permit thecorrection of convergence distortion by circuitry means with a simpleprocedure.

It is another object of the present invention to permit the correctionof pincushion distortion with more ease than has been the case in thepast.

It is a further object of the present invention to permit the correctionof convergence distortion along with the correction of pincushiondistortion.

It is a still further object of the present invention to eliminate theheretofore employed pincushion correction circuit, thereby simplifyingthe circuit construction and reducing the cost of a television set.

The above and other objects, features and advantages of the presentinvention will become more apparent from considering the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. I is a diagram showing a magnetic field distribution of a prior artdeflection yoke;

FIG. 2 is a side view showing, part in section, of an embodiment of adeflection yoke according to the present invention;

FIG. 3 is a section taken on the line III-III of FIG.

FIG. 4 shows a'magnetic field distribution of the deflection yoke shownin FIG. 2;

FIG. 5 is a side view of another embodiment comprising three of thecontiguously arranged deflection coil units shown in FIG. 3; 7

FIG. 6 shows a magnetic field distribution of the deflection yoke shownin FIG. 5;

FIG. 7 is a side view showing, part in section, another embodiment ofthis invention comprising a plurality of contiguously arrangeddeflection coil units;

FIGS. 8a, 8b and 8c show the magnetic field distributions on the crosssection of the respective deflection coil units of FIG. 7;

FIG. 9 is a section showing the wiring distribution of the deflectioncoil unit of FIG. 7 taken along the plane perpendicular to the tubeaxis;

FIG. 10 showsa magnetic field distribution of the deflection yoke shownin FIG. 11;

FIG. 11 is a side view showing, part in section, a deflection yokehaving the field distribution characteristic shown in FIG. 10 andconstituting one form of the practical application of the deflectionyoke shown in FIG.

FIG. I2 is a side view showing, part in section. another embodiment ofthe deflection yoke of the invention, wherein the distance between twodeflection coil units is adjustable;

FIG. I3 is a side view of another embodiment of the deflection yoke ofthe invention, wherein the distance between the opposing end faces alongthe tube axis differs between the electron gun side and the screen side;

FIG. 14 is a section taken along the line XIVXIV of FIG. 13;

FIG. 15 is a section taken along the line XVXV of FIG. 13;

FIG. 16 is a side view of another embodiment of the deflection yoke ofthe invention, wherein that portion called a window having no coilwindings therein differs in space between the electron gun side and thescreen side;

FIG. I7 is a section taken along the line XVIIXVII of FIG. I6;

FIG. 18 is a section taken along the line XVIII-X- VIII of FIG. I6; and

FIG. 19 is a fractional explanatory view of another embodiment of thedeflection yoke of the invention. wherein there is a difference in coilpitch angle between the electron gun side and the screen side.

Referring now to FIG. I of the drawing, there is shown a magnetic fielddistribution of a conventional deflection yoke. In the figure. theabscissa represents the distance in axial direction and the ordinaterepresents the magnitude of the magnetic field. The curve 0 indicatesthe magnetic field distribution in the axial direction of the deflectionyoke and the curve h indicates the magnetic field distribution along thesection perpendicular to the axis of the deflection yoke. The por tionsof the curves a and b above the horizontal line indicate the pincushionfield regions, while those portions below the horizontal line indicatethe barrel field regions. The strength of each of these regions isindicated by its distance from the horizontal line. The pincushion fieldregion of the deflection yoke produces a barrel distortion in thepicture, while the barrel field region produces a pincushion distortionin the picture.

It is well known that the deflection field must be uniform to satisfythe convergence characteristic and such a uniform field may beaccomplished by distributing the windings in what is known as a cosinedistribution. However, the magnetic field at the ends of a coil offinite length tends to take the formof a barrel field due to thebreaking out of the magnetic field and therefore this situation must becompensated for by making the magnetic field inside the coil to take theform of a pin cushion field to some extent. Accordingly, the magneticfield distribution of a conventional deflection yoke takes the form asshown in FIG. I. The pincushion field regions provided by the portionsof the curve b above the horizontal line in FIG. I distort the shape ofa circular beam spot into an oval form. On the other hand, the barrelfield region provided by the portion of the curve b below the horizontalline also distorts the beam spot from its circular shape into an ovalform. In

this case, however, the magnetic fields of the respective regions act inthe opposite directions. Therefore, if the area of the portion of thecurve b above the horizontal line is equal to that of the other portionof the curve [1 below the horizontal line, no beam spot distortion willtake place and hence there will be no occurrence of convergencedistortion.

Also, with respect to the pincushion distortion characteristic, even theuniform magnetic field produces a rather pincushion-shaped picture. Withthese points in mind, it is evident from consideration of FIG. I that asmentioned earlier, in the vicinity of the peak of the magnetic fielddistribution in the axial direction of the deflection yoke (curve a),the magnetic field distribution on the section taken at right angles tothe yoke axis forms a pincushion field, while, at the skirts of theaxial magnetic field distribution (curve a), the magnetic fielddistribution on the section taken at right angles to the yoke axis(curve b) forms a barrel field. Consequently, a pincushion distortion iscaused in the picture due to the effect of the barrel field region atthe skirt on the screen side of the axial magnetic field distribution.

The present invention stems from the recognition of this fact that apincushion distortion is produced in the picture by the screen-sidebarrel field region of the deflection yoke. Thus, according to thepresent invention, the screen-side deflection field of a deflection yokeis distributed in a pincushion field distribution to correct pincushiondistortion of the picture and at the same time the deflection field atthe central portion of the deflection yoke or on the electron gun sideof the central portion is distributed in a barrel field distribution incorrespondence with the pincushion field distribution on the screenside, thereby easily accomplishing the correction of convergencedistortion along with the above-mentioned correction of pincushiondistortion.

Referring now to FIG. 2 of the drawings illustrating an embodiment ofthe present invention, numerals 1 and 2 designate deflection yokes eachhaving horizontal and vertical deflection coils. The deflection yokes 1and 2 are arranged side by side in the axial direction of a cathode raytube and are put together by a C-shaped spring 3. The spring 3 isprovided with square projections 4. The square projections 4 are fittedin slits 6 formed in a housing holding the deflection yokes 1 and 2 inplace. The housing 5 is clamped on the neck portion of the cathode raytube by a band 7.

In FIG. 3, numeral 8 designates a ring core of ferromagnetic materialconstituting a part of the deflection yoke 2, 9 main deflection coils,l0 auxiliary deflection coils. For purposes of clarification, the coilsshown in the figure have a fewer number of turns than the actual numberof turns and the coils on the outside of the core 8 are not shown sincethey are not necessary for the purposes of this discussion. The maindeflection coil 9 is uniformly wound on the core 8, while the auxiliarydeflection coil is wound respectively to overlap the main deflectioncoil 9 at the central portion and the outer sides thereof.

Here, the auxiliary deflection coil 10 at the central portion of themain deflection coil 9 is designated as 10a and the auxiliary deflectioncoil 10 at the outer sides of the main deflection coil 9 is designatedas 10b.

With the arrangement described above, let it be assumed that thedirection of current flow in the auxiliary deflection coil 10a isopposite to that in the outer side auxiliary deflection coil 10b andthat the direction of current flow in the auxiliary deflection coil 10bis the same as in the main deflection coil 9. AC cordingly. at thecentral portion of the main deflection coil 9. the main deflection coil9 and the auxiliary deflection coil 10a produce magnetic fields in suchdirections which cancel each other, while, at the outer sides of themain deflection coil 9, magnetic fields are produced in such directionsthat they are added together. As a result. the deflection field of thedeflection yoke 2 is distributed in a barrel field distribution. On thecontrary, if it is so arranged that the direction of current flow in theauxiliary deflection coil 10a at the central portion of the maindeflection coil 9 is the same as the main deflection coil 9, then, atthe central portion of the main deflection coil 9. the main deflectioncoil 9 and the auxiliary deflection coil 10a produce magnetic fields insuch directions that they are added together, while. at the outer sidesof the main deflection coil 9. magnetic fields are produced in suchdirections which cancel each other. Consequently, the deflection fieldof the deflection yoke 2 is distributed in a pincushion fielddistribution. This also applies to the other deflection yoke l. Sincethe direction ofcurrent flow in the auxiliary deflection coil portionsand 10b is opposite to each other, the intensity of the axial magneticfield is constant. In other words, the magnetic field distribution onthe transverse section can be changed without changing the form of themagnetic field distribution in the axial direction of the tube. This inturn means that the deflection characteristic can be changed withoutchanging the deflection amplitude.

In FIG. 2, for example. if the direction of current flow in each of theauxiliary deflection coils in the deflection yoke l is selected so thatthe magnetic field distribution of this rear (electron gun side)deflection yoke I produces a barrel magnetic field and if the directionof current flow in each of the auxiliary deflection coils of the front(screen side) deflection yoke 2 is selected so that the magnetic fielddistribution of the deflection yoke 2 provides a pincushion magneticfield. a magnetic field distribution as shown in FIG. 4 results.

In FIG. 4, the curve a indicates an axial magnetic field distributionand the curve b indicates a magnetic field distribution on the sectionperpendicular to the tube axis. The occurrence of pincushion distortionis proportional to the distance between the curve b, and the abscissa.Since a difference in area between the pincushion region and the barrelregion is responsible for the production of convergence distortion, thepincushion and convergence distortions can be corrected as desired byadjusting the ratio and intensity of current flow in each of therespective auxiliary deflection coils of the deflection yokes l and 2.

As above described, according to this embodiment,

the correction of both pincushion and convergence distortions can beaccomplished by means of two deflection coil units which are arrangedside by side in the axial direction of the tube and are providedrespectively with main and auxiliary deflection coils and in which theratio and intensity of current flow in each of the auxiliary deflectioncoils of the respective deflection coil units are changed as desired. Inthis way, the pincushion correction circuit --which has heretofore beennecessary can be eliminated. This simplifies the circuit constructionand thus permits a reduction in the manufacturing cost.

FIG. 5 shows another embodiment of the present invention. The embodimentof FIG. 5 comprises three deflection yokes each having the same main andauxiliary deflection coils 9 and 10 as in the first embodiment andarranged side by side in the axial direction of a cathode ray tube. Thedirection of current flow in each of the auxiliary deflection coils isselected so that the magnetic field of a central deflection yoke I I isdistributed in a barrel field distribution. The direction of currentflow in each of the auxiliary deflection coils of deflection yokes l2and 13 arranged on either side of the central deflection yoke 11 is sochosen that the magnetic fields of the deflection yokes l2 and I3 aredistributed in a pincushion field distribution. FIG. 6 shows themagnetic field distribution curves for this embodiment constructed asabove described. In other words, in the vicinity of the peak of theaxial magnetic field distribution, i.e., the curve athe magnetic fielddistri bution on the section taken at right angles to the tube axis,i.e., the curve b takes the form of a barrel magnetic field and thetransectional magnetic field distributions (curve b at'the skirts of theaxial magnetic field distribution (curve a take the form of a pincushionmagnetic field. Thus, by adjusting the intensity and ratio of currentflow in each of the auxiliary deflection coils of the respectivedeflection yokes so as to make the area of both the barrel andpincushion regions equal to each other, a deflection yoke which is freefrom both pinchusion and convergence distortions can be provided.

FIG. 7 is still another embodiment of the present invention. Theembodiment of FIG. 7 comprises a pluralityof deflection yokesubassemblies contiguously arranged irzfie axial direction of a cathoderay tube. The construe on of this embodiment is such that the centraldeflection yoke subassembly has a barrel magnetic field distribution andthe deflection yoke subassembly on each side of the central subassemblyhas a pincushion magnetic field distribution. The embodiment will now beexplained in greater detail with reference to FIG. 7.

In the figure, numeral designates a deflection yoke comprising aferromagnetic core 2|, three sets of horizontal deflection coils 23, 24and for horizontally deflecting an electron beam in 'a cathode ray tube22 and three sets of vertical deflection coils 26, 27 and 28 forvertically deflecting the electron beam. The horizontal deflection coils23, 24 and 25 and the vertical deflections coils 26, 27 and 28 arearranged contiguously in the axial direction of the tube.

FIGS. 80, 8b and 8c show respectively the magnetic field distributionson the sections taken at right angles to the tube axis along the linesVIIIa-VIIIa, VIIIb- VIII!) and VIIIc'VIIIc of the horizontal andvertical deflection coils 23 and 26, the horizontal and verticaldeflection coils 24 and 27, and the horizontal and vertical deflectioncoils 25 and 28, respectively. FIGS. 8a and 80 show respectively apincushion field distribution and FIG. 8b shows a barrel fielddistribution.

Next, a method of producing pincushion and barrel magnetic fields willbe explained. Referring now to FIG. 9, there is shown a windingdistribution when the deflection coils are cut through in a planeperpendicular to the tube axis. With the winding distribution shown inFIG. 9, let it be assumed that n represents a winding density at a givenangle [3. Then. if n =11 cos '"B and m I. the deflection coil exhibits apincushion field distribution. whereas if m I. the deflection coilexhibits a barrel field distribution. In the above equation. nrepresents a winding density when the angle ,8 is zero. Therefore, itfollows that in the deflection yoke 20 of FIG. 7, the deflection coils23, 26 and 25, 28 have been wound with the winding distributionsproviding m I, while the deflection coils 24, 27 have been wound withthe winding distribution providing m l. The value of m for therespective coils must be selected in such a manner that the occurrenceof both pincushion and convergence distortions may be prevented. Thus.if the magnetic field produced by the central coil unit is distributedin a barrel field distribution and the magnetic field produced by thecoil unit on each side ofthe central coil unit is distributed in apincushion field distribution and if the intensity of the respectivemagnetic fields is adjusted by a suitable winding distribution. thenthere results a deflection yoke which is free from both pincushion andconvergence distorions.

While the embodiment of FIG. 7 has been shown as applied to a saddletype deflectionyoke, the present invention is not limited to it and thepresent invention can be equally applied. for example. tosaddle-toroidal deflection coils and toroidal-toroidal deflection coilswith equal effectiveness.

On the other hand. an increase in the deflection angle for a deflectionyoke has the effect of moving the peak of an axial magnetic fielddistribution to the rear (to the electron gun side) as shown by thecurve 11 in FIG. 10. In this case, the transectional magnetic fielddistribution may take a form as shown by the curve b in FIG. 10. Toaccomplish such a magnetic field distribution, a deflection yoke may becomposed of two deflection coil units. In this arrangement. therespective deflection coils may be wound in accordance with the mannerof the embodiment shown in FIG. 7 so that the deflection field of therear (electron gun side) deflection coil unit consists of a barrelmagnetic field and the deflection field of the front (screen side)deflection coil unit consists of a pincushion magnetic field. One formof this kind of arrangement is shown in FIG. II.

In the embodiment of FIG. 11, numeral 30 designates a ferromagneticcore, 3] horizontal deflection coils wound on the electron gun side witha barrel magnetic field distribution, 32 horizontal deflection coilswound on the screen side with a pincushion magnetic field distribution,33 vertical deflection coils wound on the electron gun side with abarrel magnetic field distribution, 34 vertical deflection coils woundon the screen side with a pincushion magnetic field distribution.

The horizontal and vertical deflection coils 31 and 33 on the electrongun side and the horizontal and vertical deflection coils 32 and 34 onthe screen side are arranged side by side in the axial direction of thetube.

Further, a deflection yoke with a magnetic field dis tributionsubstantially as shown in FIG. 6 may be provided, if two deflectionyokes each thereof having separately a magnetic field distribution asshown in FIG. I

are arranged apart from each other.

One form of this arrangement is shown in FIG. I2. In the embodiment ofFIG. I2, numeral 40 designates a deflection yoke subassembly disposed atthe rear, i.e., on the electron gun side, and numeral 41 designates adeflection yoke assembly disposed at the front, i.e.. on the screen sideat a distance from the deflection yoke assembly 40. The deflection yokeis composed of the deflection yoke subassemblies and 41. The reardeflection yoke subassembly 40 consists of a ferromagnetic core 42 andhorizontal and vertical deflection coils 43 and 44 having a pincushionfield distribution. The front deflection yoke subassembly 41 consists ofa ferromagnetic core 45 and horizontal and vertical deflection coils 46and 47 having a pincushion field distribution. The deflection yokesubassemblies 40 and 41 are joined together by a metal joint 48. One endof the metal joint 48 is secured to the deflection yoke subassembly 41and an elongated axial slit 49 is provided at the other end adjoiningthe deflection yoke subassembly 40 so that the deflection yokesubassembly 40 slides in the slit 49 to adjust the distance between thedeflection yoke subassemblies 40 and 41. By adjusting the distancebetween the deflection yoke subassemblies 40 and 41, the area of thecurve [1 below the abscissa line. i.e., the barrel field distributioncan be adjusted as desired. In other words, the correction ofconvergence distortion can be effected through the adjustment ofdistance between the two deflection yoke subassemblies. Of course. thecorrection of pincushion distortion is also possible.

FIG. 13 illustrates still another embodiment of the present invention.In the figure, numeral 50 designates a deflection yoke comprising a pairof deflection coil units 51 and 52 each having horizontal and verticaldeflection coils. A distance D between opposed end faces 53 and 54 ofthe deflection coil units 51 and 52 along the tube axis (the line a-a)is made so that if the distance D at the rear (electron gun side) isdesignated D and D represents the distance D at the front (screen side),then there is a relation In other words, the distance D graduallydecreases from the rear (electron gun side) toward the front (screenside). With this construction, it is possible for the deflection yoke 50to produce a barrel field distribution at its rear portion and apincushion field distribution at its front portion.

FIGS. 14 and 15 show respectively the sections taken along the linesXlVXIV and XV-XV of the deflec-- tion yoke 50 shown in FIG. 13. In FIGS.14 and 15, (1

indicates the angle of what is known as a window where there is nowinding.

FIGS. 16 through 18 illustrate still another embodiment of the presentinvention. FIG. 17 is a section taken along the line XVII-XVII of thedeflection yoke shown in FIG. 16, and FIG. 18 is a section taken alongthe line XVIII-XVIII of the deflection yoke shown in FIG. 16. As will beseen from these figures, a distance D between opposed end faces 62 and63 of a pair of deflection coil units and 61 along the tube axis isuniform. The construction of this embodiment is such that if 01represents the angle of the central portion of the deflection coil units60 and 61, Le, the portion known as a window with no winding disposedtherein, a, represents the angle at the rear portion (electron gun side)of the coil units and (1 represents the angle of the front portion(screen side), then there is a relation In other words, the angle aincreases gradually from the rear portion toward the front portion.

With this construction, the same magnetic field distribution as thedeflection yoke 50 shown in FIG. 13 can be provided for the deflectionyoke 64, that is. a barrel field distribution at the rear portion and apincushion field distribution at the front portion of the de' flectionyoke 64 can be obtained. The same results can be obtained by thecombination of the methods of FIGS. 13 and 16.

FIG. 19 illustrates still another embodiment of the present invention.FIG. 19 shows a principal part of a toroidal deflection yoke. In thefigure. numeral designates a ferromagnetic core, 7] a coil wound on theferromagnetic core 70. In this embodiment. the coil 71 is wound so thatif [3 represents the angle of a single pitch of the coil 71, Li,represents the angle [3 at the rear portion of the coil and B representsthe angle [3 at the front portion (screen side), then there results arelation 3, B With this arrangement. similarly with the embodiment ofFIG. 13, a barrel field distribution at the rear portion and apincushion field distribution at the front portion can be obtained. Inother words. the simultaneous correction of pincushion and convergencedistortions can be effected.

It will thus be seen from the foregoing description that the deflectionyoke arrangements of very simple construction according to the presentinvention can be used to effect the simultaneous correction ofpincushion and convergence distortions. It will also be seen that thepresent invention eliminates the heretofore used pincushion correctioncircuit with resultant simplificiation of the circuit construction and areduction in the manufacturing cost of television sets.

What we claim is:

1. A deflection yoke comprising a plurality of deflection coils arrangedcontiguously along a tube axis, and wherein the deflection field of saiddeflection coil located in the center of said plurality of deflectioncoils is distributed in a barrel magnetic field distribution. and thedeflection field of said deflection coil located on each side of saidcentrally located deflection coil is distributed in a pincushionmagnetic field distribution.

2. A deflection yoke comprising a plurality of deflection coils arrangedcontiguously along a tube axis, and wherein the deflection field of saiddeflection coil located on an electron gun side is distributed in abarrel magnetic field distribution, and the deflection field of saiddeflection coil located on a screen side is distributed in a pincushionmagnetic field distribution.

3. A deflection yoke comprising a plurality of deflection coil unitsarranged contiguously in the direction of a tube axis, wherein each ofsaid plurality of deflection coil units comprises horizontal andvertical deflection coils each thereof including a main coil wound in aunifomily distributed winding and an auxiliary coil overlapping saidmain coil to adjust a magnetic field distribution on a section taken atright angles to said tube axis, and wherein said auxiliary coil is woundso that the direction of current flow in said auxiliary coil overlappingthe central winding of said main coil is opposite to that in saidauxiliary coil overlapping the outer side winding portions of said maincoil.

4. A deflection yoke according to claim 3, wherein the direction ofcurrent flow in each of said auxiliary coils of said deflection coilunit located on an electron gun side is selected so that said deflectioncoil unit located on the electron gun side has its deflection fielddistribued in a barrel magnetic field distribution, and

wherein the direction of current flow in each of said auxiliary coils ofsaid deflection coil unit located on a screen side is selected so thatsaid deflection coil unit located on the screen side has its deflectionfield distributed in a pincushion magnetic field distribution.

5. A deflection yoke according to claim 3, wherein the direction ofcurrent flow in each of said auxiliary coils of said deflection coilunit located in the center of said plurality of deflection coil units isselected so that said centrally located deflection coil unit has itsdeflection field distributed in a barrel magnetic field distribution,and wherein the direction of current flow in each of said auxiliarycoils of said deflection coil unit located on each side of saidcentrally located deflection coil unit is selected so that saiddeflection coil unit on each side of said centrally located deflectioncoil unit has its deflection field distributed in a pincushion magneticfleld distribution.

6. A deflection yoke according to claim 4, wherein the direction ofcurrent flow in the auxiliary coil portions wound on the outer sidewinding portions of the main coils in the deflection coil unit locatedon the electron gun side is the same with that in said main coils.

7. A deflection yoke according to claim 4, wherein the direction ofcurrent flow in the auxiliary coil portions wound on the central windingportions of the main coils in the deflection coil unit located on thescreen side is the same with that in said main coils.

8. A deflection yoke according to claim 5, wherein same with that insaid main coils.

10. A deflection yoke according to claim 3, wherein the plurality ofdeflection coil units are held together by a C-shaped retaining member.and wherein a projection formed on each side of said retaining member isfit in the associated slit in a housing accommodating said deflectioncoil units.

11. A deflection yoke according to claim 1, wherein n represents awinding density at a given angle [3 of the winding distribution of thedeflection coil unit within a plane perpendicular to the tube axis. saidn being given by n n cos '"B, where n represents a winding density whensaid angle [3 is zero. wherein the deflection coil unit of m 1 iscentrally located. and wherein the deflection coil unit of m I islocated on each side of said centrally located deflection coil unit.

12. A deflection yoke according to claim 2, wherein n represents awinding density at a given angle B ofthe winding distribution of thedeflection coil unit within a plane perpendicular to the tube axis. said11 being given by n n cos "'B, where n represents a winding density whensaid angle [3 is zero, wherein the deflection coil unit of m 1 islocated on the electron gun side. and wherein the deflection coil unitof m 1 is located on the screen side.

13. A deflection yoke according to claim 1. wherein each of the twodeflection coils having a pincushion magnetic field distributioncomprises a plurality of coils arranged contiguously with a distancetherehetween in the direction of the tube axis, and wherein saiddistance between said deflection coils is adjustable.

14. A deflection yoke according to claim 13, wherein a metal joint issecured at one end thereof to one of the deflection coils and is formedwith a slit at the other end thereof. and wherein the other of thedeflection coil units is movably mounted in said slit. whereby thedistance between said deflection coil units is adjustable.

1. A deflection yoke comprising a plurality of deflection coils arrangedcontiguously along a tube axis, and wherein the deflection field of saiddeflection coil located in the center of said plurality of deflectioncoils is distributed in a barrel magnetic field distribution, and thedeflection field of said deflection coil located on each side of saidcentrally located deflection coil is distributed in a pincushionmagnetic field distribution.
 2. A deflection yoke comprising a pluralityof deflection coils arranged contiguously along a tube axis, and whereinthe deflection field of said deflection coil located on an electron gunside is distributed in a barrel magnetic field distribution, and thedeflection field of said deflection coil located on a screen side isdistributed in a pincushion magnetic field distribution.
 3. A deflectionyoke comprising a plurality of deflection coil units arrangedcontiguously in the direction of a tube axis, wherein each of saidplurality of deflection coil units comprises horizontal and verticaldeflection coils each thereof including a main coil wound in a uniformlydistributed winding and an auxiliary coil overlapping said main coil toadjust a magnetic field distribution on a section taken at right anglesto said tube axis, and wherein said auxiliary coil is wound so that thedirection of current flow in said auxiliary coil overlapping the centralwinding of said main coil is opposite to that in said auxiliary coiloverlapping the outer side winding portions of said main coil.
 4. Adeflection yoke according to claim 3, wherein the direction of currentflow in each of said auxiliary coils of said deflection coil unitlocated on an electron gun side is selected so that said deflection coilunit located on the electron gun side has its deflection fielddistribued in a barrel magnetic field distribution, and wherein thedirection of current flow in each of said auxiliary coils of saiddeflection coil unit located on a screen side is selected so that saiddeflection coil unit located on the screen side has its deflection fielddistributed in a pincushion magnetic field distribution.
 5. A deflectionyoke according to claim 3, wherein the direction of current flow in eachof said auxiliary coils of said deflection coil unit located in thecenter of said plurality of deflection coil units is selected so thatsaid centrally located deflection coil unit has its deflection fielddistributed in a barrel magnetic field distribution, and wherein thedirection of current flow in each of said auxiliary coils of saiddeflection coil unit located on each side of said centrally locateddeflection coil unit is selected so that said deflection coil unit oneach side of said centrally located deflection coil unit has itsdeflection field distributed in a pincushion magnetic fielddistribution.
 6. A deflection yoke according to claim 4, wherein thedirection of current flow in the auxiliary coil portions wound on theouter side winding portions of the main coils in the deflection coilunit located on the electron gun side is the same with that in said maincoils.
 7. A deflection yoke according to claim 4, wherein the directionof current flow in the auxiliary coil portions wound on the centralwinding portions of the main coils in the deflection coil unit locatedon the screen side is the same with that in said main coils.
 8. Adeflection yoke according to claim 5, wherein the direction of currentflow in the auxiliary coil portions wound on the outer side coilportions of the main coils in the centrally located deflection coil unitis the same with that in said main coils.
 9. A deflection yoke accordingto claim 5, wherein the direction of current flow in the auxiliary coilportions wound on the central winding portions of the main coils in thedeflection coil unit located on each side of the centrally locateddeflection coil unit is the same with that in said main coils.
 10. Adeflection yoke according to claim 3, wherein the plurality ofdeflection coil units are held together by a C-shaped retaining member,and wherein a projection formed on each side of said retaining member isfit in the associated slit in a housing accommodating said deflectioncoil units.
 11. A deflection yoke according to claim 1, wherein nrepresents a winding density at a given angle Beta of the windingdistribution of the deflection coil unit within a plane perpendicular tothe tube axis, said n being given by n n0 cos m Beta , where n0represents a winding density when said angle Beta is zero, wherein thedeflection coil unit of m < 1 is centrally located, and wherein thedeflection coil unit of m > 1 is located on each side of said centrallylocated deflection coil unit.
 12. A deflection yoke according to claim2, wherein n represents a winding density at a given angle Beta of thewinding distribution of the deflection coil unit within a planeperpendicular to the tube axis, said n being given by n n0 cos m Beta ,where n0 represents a winding density when said angle Beta is zero,wherein the deflection coil unit of m < 1 is located on the electron gunside, and wherein the deflection coil unit of m > 1 is located on thescreen side.
 13. A deflection yoke according to claim 1, wherein each ofthe two deflection coils having a pincushion magnetic field distributioncomprises a plurality of coils arranged contiguously with a distancetherebetween in the direction of the tube axis, and wherein saiddistance between said deflection coils is adjustable.
 14. A deflectionyoke according to claim 13, wherein a metal joint is secured at one endthereof to one of the deflection coils and is formed with a slit at theother end thereof, and wherein the other of the deflection coil units ismovably mounted in said slit, whereby the distance between saiddeflection coil units is adjustable.